66 
Mr. Airy's remarks on a correction of the 
of the centre, liable to error. The error of the equation of 
the centre is found to be so small that it may be neglected : 
but the errors of the epoch and place of the perigee are 
considerable. 
The first part of the operation was to deduce from the 
errors in M , , the corresponding errors in longitude. This 
was done by multiplying them by 15 sec. 23 0 28' cos. 1 dec. ; 
the multiplication by sec. 23 0 28' was however reserved to 
the end, when the results are multiplied by it. The next 
was, to give the errors which would be occasioned by assumed 
errors in the epoch, the place of the perigee, and the greatest 
equation of the centre. As the tables contain the variation of 
the equation of the centre for a variation of 1 o' in the mean 
anomaly, and for one of — 17", 18 in the greatest equation, 
this was very easily effected. 
Supposing then that the epoch ought to be increased by 
x" , the mean anomaly by y x 10', and the greatest equation 
of the centre by — ■ % x 17", 18, I get the following equations, 
each of which is erroneous to the amount of the error of 
observation. The first side (as was mentioned) ought to be 
multiplied by sec. 23 0 28 f . 
10,57 = x — y x 19,7 — ^ x 0,48 
11.87 = x —y x 19,6 + % x 2,1 
10,38 — x — y x 19,4 + z x 2,91 
13.87 = x — y x 19,1 + % x 4,59 
12,8 = x — <y x 18,9 z x 4,87 
10,31 = x — y x 16,9 + z x 8,75 
8,94 = x — y x 16,7 + z x 8 >99 
12,49 = x — y x 15,6 + z x 10,43 
10,76 = x — y x 15,4 + % x 10,65 
8,43 = x — yxi 4 +£xi 2 
